Does anyone know how to edit cameras? I want to create a video from inside the car which is like a video camera on the roll bar.
Not yet but you will be able to soon
When v1.0 is released (we're on 0.7 at the moment, so not long), the modding tools will also be released which allows new user-created cars and tracks to be added to the game.
There are plenty of WIP cars to look forward to though, including the one in my avatar.